Daniel Popkin, MD, PhD, an assistant professor of dermatology at the Case Western Reserve University in Cleveland, and colleagues focused on 275 pairs of twins: 233 identical twin pairs and 42 fraternal twin pairs. All were between 18–80 years old, and most were from Ohio, Pennsylvania, and the northeastern United States. All participants completed lifestyle and medical history surveys, and underwent dermatological screening before receiving their rosacea score, which ranged from absent to severe.

The investigators concluded that genetics appeared to contribute to 46% of rosacea risk. The rest of the observed risk was attributed to greater lifetime ultraviolet radiation exposure, older age, a higher body mass index, smoking, alcohol consumption, and cardiovascular disease and/or skin cancer.

"We now have strong evidence for the first time that there is clearly a genetic contribution," Popkin told HealthDay. And with a strong family history of rosacea, "more attention should be paid to environmental factors, and seeking medical advice can help quite a bit," he added.